This year I got it in my head to build a window display. It's pretty simple, a landscape made from cardboard along with a few set-pieces made from carved and painted styrofoam. The big 'attraction' is a floating ghostly skull which hovers between the archway in the front. It's done using 'Peppers ghost', an old stagecraft illusion which is used heavily by David Hoffas. I projected a simple animation on a sheet in the background using a fresnel lens and a tv. Here's a terrible picture of it at night. You can sort of see the skull there.
And some details:
The Archway with a little snippet of the TV which helps create the Peppers Ghost illusion.
Anyone else do any fun decorating this year?